by Calum MacLeod, USA TODAY

by Calum MacLeod, USA TODAY

BEIJING - In the first case of its kind involving foreigners, a British citizen and his American wife go on trial in Shanghai on Friday on charges of conducting an illegal investigation for GlaxoSmithKline in connection with allegations of bribery by the British pharmaceutical giant to boost sales in China.

In an interview Monday with USA TODAY, Harvey Humphrey, the son of Peter Humphrey, 58, and Yu Yingzeng, 61, said he is "cautiously optimistic" that his parents would receive a light sentence and be released next month after more than a year in detention.

The company said it hired the couple in April 2013 to investigate a security breach concerning a former employee's suspected e-mails that alleged widespread bribery at GSK, and circulation of a sex tape of GSK's former top China executive, Mark Reilly, with his girlfriend.

Humphrey and Yu were formally arrested last August and indicted last month on charges of conducting an illegal investigation. Their Shanghai-based consultancy, ChinaWhys, "illegally trafficked a huge amount of personal information on Chinese citizens" from 2009 to 2013, according to city prosecutors, as quoted by Xinhua, the state news agency.

After a 10-month investigation, Chinese police have also accused GSK of corruption on a huge scale, offering bribes to boost its China sales and inflating drug prices to offset the bribery expenses, Xinhua said. Reilly, 52, a married father of two, voluntarily returned to China last summer to cooperate with authorities and was subsequently detained.

In a statement issued last month, GSK said that after investigations into the allegations, "some fraudulent behavior relating to expense claims was identified, and this resulted in employee dismissals and further changes to our monitoring procedures in China."

"However, this investigation did not find evidence to substantiate the specific allegations made in the whistle-blower e-mails," the company said.

GSK added that it hired ChinaWhys to investigate "a serious breach of privacy and security related to the company's China general manager. They were not hired to investigate the substance of the allegations of misconduct made by the whistle-blower."

"We have zero tolerance for any kind of corruption in our business, and we have many policies, procedures and controls in place to monitor this and take action against any breaches," the company statement said.

Harvey Humphrey, 19, the accused couple's only child, was allowed to visit his parents last Friday for the first time in more than a year. Humphrey, who was born in Boston and has dual U.S-United Kingdom citizenship, said their health appeared "mediocre" but "stable."

Humphrey said he expects a guilty plea, "as that usually works best in China," and hopes for a light sentence that could see them released as soon as September.

The "best-case scenario would be the number of days they have served plus a few more days," he told USA TODAY in Beijing. After initial concern that authorities would hold a closed trial, as is common in China, Humphrey will be allowed to attend, along with consular officers from the USA and U.K., he said. Foreign media are unlikely to be given access to the trial.

When they are released, Humphrey said he expects his parents, who had intended to retire this summer, will move to the U.K., where he will start college this fall. Humphrey has delayed his planned mechanical engineering studies for a year to help his parents.

A near-fluent Mandarin speaker who has spent his whole life in mainland China or Hong Kong and calls Beijing home, Humphrey said he would still consider a career in China, despite his parents' ordeal.